This invention relates to collapsible support structures which are utilized to support highway signs, barricades, flashing lights and the like and, more particularly, to support structures which collapse, without flying apart, when struck by a moving vehicle.
Indicating devices such as signs, barricades, and flashing lights are used on or adjacent to highways to indicate construction areas, to block lanes, to warn motorists of road hazards, etc. Support for these indicating devices is commonly provided by a rigidly constructed metal framework. When such an indicating device and its associated support are accidentally struck by a vehicle traveling along the highway, the indicating device and support, or parts thereof, can be propelled in various directions causing injury to the vehicle occupants, workmen and pedestrians in the area, and occupants of oncoming vehicles.
It is desired to provide a support structure for highway indicating devices which creates a minimal risk of injury when struck by a vehicle. It has been found that the risk of injury is reduced when the support structure collapses to a horizontal position upon impact by a vehicle, thus allowing the vehicle to pass over the support structure and the attached indicating device. Furthermore, the support structure must be configured to hold together after impact so that flying parts do not cause personal injury and must have sufficient strength to withstand rough handling by highway workers. U.S. Pat. No. 4,183,695, issued Jan. 15, 1980, to Wilcox discloses a barricade which collapses when struck from the front or rear. However, the disclosed barricade does not collapse when subjected to a sideways impact.
Another approach is to configure the support structure so that the attached indicating device passes over the top of the vehicle after impact. This configuration is particularly useful for signs which are taller than vehicles. Typically, the support structure detaches from its base near ground level upon impact.